1. Field of the Invention
The present invention relates to a wire bonder, and more particularly, to a wire bonder and that wire bonding method equipped with an automatic inspection function for an electrode (pad) on a semiconductor chip (IC chip), lead and wire spread between said pad and lead in the assembly process of a semiconductor device.
2. Description of the Prior Art
In the assembly process during manufacturing of semiconductor integrated circuits (IC) and large-scale integrated circuits (LSI), a first bonding point in the form of an electrode (pad) on a semiconductor chip (IC chip) and a second bonding point in the form of a lead are connected by bonding using gold wire or wire made of copper or aluminum.
This bonder first produces an electrical discharge by applying a high voltage between the end of a protruding wire and a discharge electrode (electric torch) from a bonding tool in the form of a capillary. The end of the wire is then melted by the energy of that discharge resulting in the formation of a ball on the end of the wire that has been inserted into the capillary. By then applying ultrasonic vibrations while bringing the ball held on the end of the capillary in contact with an electrode (pad) on a semiconductor chip, the wire is connected to the bonding point.
In order to confirm whether a wire that has been automatically bonded by a bonder has been reliably connected to the pad or lead, or confirm whether the connected wire has formed a loop on the wire connecting the pad and lead in the prior art, the bonded lead frame is continuously or at fixed intervals removed from the assembly process followed by the performing of an inspection for non-defective or defective products by an inspector using a microscope and so forth in a separate inspection process. In this inspection process, an inspection is performed as to determine whether the wire has been reliably bonded, and namely, a misattachment inspection is also performed to determine if the wire has been broken, there are defective connections and so forth by performing a visual inspection and so on.
Moreover, an inspection is also performed using a microscope and so forth as to whether the initial ball formed on the end of the wire has been formed to the proper size as set with, for example, a keyboard. Adjustments of each section are then performed based on these inspection results.
However, in order to perform the above-mentioned inspections using a bonder of the prior art, since the bonded lead frame is removed from the assembly line and inspected in a separate inspection process, even in the case a problem such as a connection defect occurred in this inspection process, said data cannot immediately be fed back to the bonder. Consequently, this bonder has the disadvantage of producing a large number of defective products. In addition, even if this inspection data was fed back, since there is variation as to what data should be fed back depending on the inspector, this bonder also has the disadvantage of there being the risk of reliable data not being consistently fed back. Moreover, although adjustment of the bonder is required following the discovery of a defect, a considerable amount of time is required to determine what section should be adjusted even for a skilled technician. Since a considerable amount of time is required to perform this task, this impairs the stability and reliability of the bonder. Moreover, the additional disadvantage results in which the bonder, which is used for the purpose of high-speed operation, must be stopped for a long period of time in order to make adjustments during that time.
In addition, in the bonder of the prior art, since separate inspection processes are required like those described above, .the bonder of the prior art also has the disadvantage of the inspection equipment being expensive and requiring a large amount of space. In addition, it also has the disadvantage of requiring additional inspectors for performing the inspections in this inspection process.